A Swiss university, in collaboration with IBM, has launched a new water-cooled supercomputer, which IBM says uses up to 40 percent less energy than a comparable air-cooled system and which contributes waste heat to a building heating system.

The system, called Aquasar, is installed at the Swiss Federal Institute of Technology Zurich (ETH Zurich). It includes both water-cooled and air-cooled IBM BladeCenter servers for direct comparison with traditional systems. The water-cooled machines were designed and manufactured by IBM scientists in Zurich and Boblingen, Germany.

Aquasar consists of BladeCenter H chassis with a total of 33 BladeCenter QS22 servers, each carrying two IBM PowerXCell 8i processors, and nine BladeCenter HS22 servers, with two Intel Nehalem EP processors per server. Two of the chassis, holding 22 QS22 servers and six HS22 servers are water-cooled.


Aquasar servers are enclosed in IBM BladeCenter H chassis

The system's total compute power is six teraflops. It performs about 450 megaflops per watt.

According to IBM, water is 4,000 times more efficient in removing heat than air. Micro-channel liquid coolers bring 60 C water directly to the processors. This allows for thermal resistance between the processor and the water to be reduced to ensure that the processor operating temperature stays below the 85 C ceiling.

Higher coolant temperature results in higher output temperature, which allows the machine to contribute about 9 kW of thermal power to the comfort heating system of university buildings. According to IBM, this reduces Aquasar's carbon footprint by up to 85 percent.

Aquasar was built as part of a research program, studying use of waste heat from liquid-cooled supercomputers. Participants in the program are ETH Zurich, IBM Research ÔÇô Zurich and ETH Lausanne.

"With Aquasar, we make an important contribution to the development of sustainable high performance computers and computer system," said in a statement Dimos Poulikakos, head of the school's Laboratory of Thermodynamics in New Technologies. In the future it will be important to measure how efficiently a computer is per watt and per gram of equivalent CO2 production."